Sensing for respiratory circuits

ABSTRACT

Some embodiments provide a breathing assistance apparatus comprising a conduit for conveying gases therein, the conduit comprising circuitry. The circuitry may comprise at least one heater wire part to heat gases in the conduit, in use, and at least one sensor wire part comprising at least one sensor for monitoring a parameter of the gases in the conduit. There is also provided a controller to control provision of AC power or AC voltage to the heater wire part; and control selective reading of the sensor. The controller may be configured to read the sensor at or about a particular portion of the AC power waveform provided to the heater wire part.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND Field

The present disclosure generally relates to systems, apparatus andmethods for providing humidified gases to users, and more particularlyto applications thereof for use with respiratory circuits forhumidification systems that involve both sensing and driving or poweringof one or more elements, such as a heater coil.

Description of Related Art

Many gas humidification systems deliver heated and humidified gases forvarious medical procedures, including respiratory treatment,laparoscopy, and the like. These systems can be configured to controltemperature, humidity and flow rates using feedback from sensors. Tomaintain desirable properties upon delivery to a user, a breathingcircuit can have heaters associated with gas conduits where the heatersprovide heat to the gas as it flows to and/or from the user. The conduitheaters can be controlled to provide heat to the gas so that the gasarrives to the user having desirable properties such as temperatureand/or humidity. A humidification system can include a temperaturesensor to provide feedback to a humidification controller which canadjust and/or modify power delivered to the conduit heaters to achieve atarget temperature at a location along an associated conduit. Othersensors may additionally or alternatively be provided that, for example,measure any one or more of flow, pressure, or humidity, or otherproperties of gas and/or of one or more components of the system, suchas a patient interface or conduit.

Some example respiratory circuit components are disclosed in PCTApplication No. PCT/NZ2015/050028 entitled “MEDICAL TUBES FORRESPIRATORY SYSTEMS,” filed Mar. 17, 2015 and incorporated herein byreference in its entirety.

PCT Application No. PCT/NZ2013/000208 entitled “ZONE HEATING FORRESPIRATORY CIRCUITS,” filed Nov. 14, 2014 and incorporated herein byreference in its entirety, discloses respiratory circuits forhumidification systems. More particularly, arrangements are describedfor monitoring parameters within a humidification system and adjustingoperation thereof based at least in part thereon. For example, atemperature of gases in an inspiratory conduit of a respiratory circuitmay be monitored and power supplied to a heater wire for heating gasesin the inspiratory conduit adjusted accordingly.

According to some embodiments disclosed in PCT Application No.PCT/NZ2013/000208, sensor and heater wires terminate at one end of aconduit, at or proximate a cuff. This arrangement can convenientlyprovide for pneumatic connection of the conduit to a source of gaseswhile at the same time establishing electrical connections between theheater and sensor wires and wider control/power circuitry. Further, theheater and sensor wires are disclosed as being positioned adjacent oneanother along at least a portion of the length of the tube and beingconnected to common circuit boards. While this arrangement can reducethe total number of components and simplify manufacture, it has beenfound that the power supplied to the heater wires creates noise thataffects the accuracy of readings from sensors connected to the sensorwires. For infant, multi-zone embodiments disclosed inPCT/NZ2013/000208, when the patient end temperature set point is near40° C., an error in the region of ±0.3° C. may be introduced and foradult tube embodiments, around ±0.15° C. Any possible reduction in theseerrors is desirous to improve performance of the system as a whole,especially humidification aspects thereof.

SUMMARY

The systems, methods and devices described herein have innovativeaspects, no single one of which is indispensable or solely responsiblefor their desirable attributes. Without limiting the scope of theclaims, some of the advantageous features will now be summarized.

The invention is generally described herein with reference orapplication to inspiratory limbs. However, the invention is not limitedthereto and has wider application. For example, it may be applied toexpiratory limbs and/or limbs used for the purposes of providing and/orremoving gases etc during insufflation procedures. Hence reference toinspiratory limb is by way of reference only.

According to one aspect of the invention there is provided a controllerfor a breathing assistance apparatus, the breathing assistance apparatuscomprising a conduit for conveying gases therein, the conduit comprisingcircuitry, the circuitry comprising at least one heater wire part toheat gases in the conduit, in use, and at least one sensor wire partcomprising at least one sensor for monitoring a parameter of the gasesin the conduit, in use, the controller being configured to:

-   -   control provision of AC power or AC voltage to the heater wire        part; and    -   control selective reading of the sensor,    -   wherein the controller is configured to read the sensor at or        about a particular portion of the AC power waveform provided to        the heater wire part.

The controller may be arranged such that said particular portion of theAC power or voltage waveform commences at or about or after a first zerocrossing of the AC power or voltage waveform, preferably a falling zerocrossing, and at or before a second zero crossing of the AC power orvoltage waveform, the first and second zero crossings being consecutivezero crossings of the same type.

The controller may be configured to control repeating said selectivereading of the sensor, between a third and a fourth zero crossing, thesecond, third and fourth zero crossings being consecutive zero crossingsof the same type.

The controller may comprise or be communicatively couplable to a monitorto monitor the AC power or voltage waveform, wherein the controllercontrols when to selectively read the sensor based at least in part on asignal indicative of or derived from the monitored AC power or voltagewaveform. The controller may be configured to use the monitor to detecta zero crossing of the AC power or voltage waveform, preferably afalling zero crossing. The controller may be configured to use themonitor to detect a portion of the AC power or voltage waveform otherthan a zero crossing. The controller may be adapted to establish atiming of a zero crossing based at least in part on a timing of thedetected portion of the AC power or voltage waveform that is not a zerocrossing.

The controller may be adapted to establish, at least in part, a timingof the particular portion of the AC power or voltage waveform based atleast in part on one or more known and/or detected characteristics ofthe AC power waveform. Said characteristic(s) of the AC power or voltagewaveform may comprise a frequency thereof.

The at least one heater wire part may comprise at least one heater wireconnectable to said AC power or voltage. There may be two or four saidheater wires.

The at least one sensor wire part may comprise at least one sensor wire.There may be two said sensor wires. At least a portion of said sensorwire(s) may be positioned adjacent at least a corresponding portion ofsaid heater wire(s). The heater wire part and the sensor wire part maycomprise independent circuits.

The controller may comprise or be coupled to a multiplexer, wherein themultiplexer is coupled to or configured to be coupled to the sensor wirepart. The multiplexer may be coupled to a plurality of sensor wires toenable reading of corresponding sensors coupled to the sensor wires. Thecontroller may be configured to reset the multiplexer at a positiverising edge of the AC power or voltage waveform and/or during a positivephase of the AC power or voltage waveform. The controller may beconfigured to use the multiplexer to read the sensor(s) during a fallingedge of the AC power or voltage waveform.

The controller may comprise or be communicatively coupled to a memory tostore information relating to the AC power or voltage waveform, such asphase information, and/or information relating to the sensor(s) of thesensor wire part.

The controller may comprise at least two sensors, wherein the controlleris configured to control reading of a first of said sensors at or aboutor after a first zero crossing of the AC power or voltage waveform,preferably a falling zero crossing, and at or before a second zerocrossing of the AC power or voltage waveform, the first and second zerocrossings being consecutive zero crossings of the same type, and whereinthe controller is configured to control reading of a second of saidsensors at or about or after a third zero crossing and at or before afourth zero crossing, the first, second, third and fourth zero crossingsbeing consecutive zero crossings of the same type.

The conduit may comprise first and second segments or parts that areconnectable together to provide an elongated conduit, wherein thecontroller is configured to receive a signal indicative of a presenceand/or absence of the first and/or second segment and implement controldependent on which segment(s) are present and/or absent. If only thefirst segment is determined to be present, the controller may adopt afirst mode, the first mode preferably being adapted for adult usersand/or applications in which the environmental conditions aresubstantially the same along the length of the conduit. The controllermay be configured to control application of power to the at least oneheater wire part such that:

-   -   the waveform thereof transitions from flat to the negative half        of a full cycle, and/or    -   the waveform thereof transitions from the positive half of a        full cycle to flat.        If the second segment is determined to be present, the first        segment may comprise a first heater wire part and the second        segment comprises a second heater wire part, wherein the        controller may be configured to control selective application of        power to the first heater wire part during a first time period        and to control selective application of power to both the first        and second heater wire parts and/or to the second heater wire        part only in a second time period.

The controller may be adapted to control application of power:

-   -   to the first heater wire part such that the waveform thereof        transitions from flat to the first of two positive half cycles        and/or to flat following two positive half cycles, and/or    -   to the second heater wire part such that the waveform thereof        transitions from flat or off to the first of two negative half        cycles and/or to flat following two negative half cycles, and/or    -   to both heater wire parts such that the waveform thereof        transitions from flat or off to the first of two negative half        cycles and/or to flat following two negative half cycles.

The controller may be adapted to determine a frequency of the AC poweror voltage.

According to another aspect of the invention, there is provided abreathing assistance apparatus comprising:

-   -   a conduit for conveying gases therein, the conduit comprising        circuitry, the circuitry comprising:    -   at least one heater wire part to heat gases in the conduit, in        use; and    -   at least one sensor wire part comprising at least one sensor for        monitoring a parameter of the gases in the conduit; and    -   the controller of any one of the above statements.

At least one heater wire part and/or said at least one sensor wire partmay terminate at or proximate to a first end of the conduit, preferablywithin 20 mm of an end of the conduit, more preferably within 10 mm ofan end of the conduit, and more preferably still, within 5 mm of an endof the conduit, said end being the patient end of the tube, in use.

The at least one heater wire part and/or said at least one sensor wirepart may be coupled to a printed circuit board, PCB. The PCB may bepositioned inside and/or about and/or within a wall forming the conduit.The PCB may be provided at or proximate to a second end of the conduit.The or at least one said sensor may be mounted on or to the PCB.

The heater wire(s) may be associated with a least a portion of a lengthof the conduit by being provided therein and/or thereabout and/or withina wall forming the conduit.

The sensor wire(s) may be associated with a least a portion of a lengthof the conduit by being provided therein and/or thereabout and/or withina wall forming the conduit.

The breathing assistance apparatus may comprise two said heater wiresand two said sensor wires, the wires being provided in or embedded in awall of the conduit and spirally wound to be arranged in the sequenceheater wire 1, sensor wire 1, sensor wire 2 and heater wire 2.

According to another aspect of the invention there is provided arespiratory humidification system comprising:

-   -   the controller of any one of the above statements; and/or    -   the breathing assistance apparatus of any of the above        statements.

According to a further aspect of the invention there is provided amethod of respiratory humidification comprising:

-   -   controlling provision of AC power or voltage to a heater wire        part of a medical tube; and        controlling selective reading of a sensor, provided in or        coupled to or otherwise associated with the medical tube, at or        about a particular portion of the AC power or voltage waveform        provided to the heater wire part.

A medical conduit for use as the conduit referred to in any one of theabove statements.

Some embodiments provide for an inspiratory limb for a breathing circuitand/or systems and/or methods including an inspiratory limb. Theinspiratory limb described herein is particularly useful or applicableto situations where heated and humidified gases are conveyedtherethrough. According to some embodiments, the heated and humidifiedgases may pass through two distinct environments. This can be a problem,for example, in infant incubators where the temperature is significantlyhigher than the surrounding environment or where a portion of theconduit delivering the gases to the patient is under a blanket. Someembodiments disclosed herein, however, can be used in any environmentwhere heated and/or humidified gas is delivered to a patient and are notlimited to uses where the inspiratory limb passes through two distinctenvironments.

The inspiratory limb can include a first segment of the inspiratory limbthat comprises a first structure forming a conduit, the conduitconfigured to transport a humidified gas, and wherein the first segmentof the inspiratory limb includes a first heater wire part or circuit.The inspiratory limb can include a second segment of the inspiratorylimb that comprises a second structure forming a conduit configured totransport the humidified gas, wherein the second structure is configuredto mechanically couple or be otherwise joined to or made integral withthe first structure of the first segment to form an extended conduit forthe humidified gas and wherein the second segment of the inspiratorylimb includes a second heater wire part or circuit. The inspiratory limbcan include an intermediate connector that includes a connection circuitthat electrically couples the first heater wire circuit to the secondheater wire circuit, wherein the intermediate connector can be coupledto a patient-end of the first segment of the inspiratory limb and achamber-end of the second segment of the inspiratory limb to form asingle conduit for the humidified gases. The intermediate connector canbe covered by a portion of the first segment of the inspiratory limb, aportion of the second segment of the inspiratory limb, or a portion ofboth the first and second segments of the inspiratory limb such that theintermediate connector is internal to the inspiratory limb.

The inspiratory limb can be configured to operate in two heating modes.In a first heating mode, electrical power passes through theintermediate connector to provide power to the first heater wire circuitwithout providing power to the second heater wire circuit. In a secondheating mode, electrical power passes through the intermediate connectorto provide power to both the first heater wire circuit and the secondheater wire circuit. For example, the intermediate connector can includeelectrical components configured to direct electrical power alongdifferent paths based at least in part on a direction of current flowand/or a polarity of voltage. The intermediate connector can includeconductive tracks which can provide a short (e.g., a direct electricalconnection with no intervening electrical components) between one ormore wires in the first heater wire circuit and one or more wires in thesecond heater wire circuit. The intermediate connector can includeconductive tracks which electrically couple one or more wires in thefirst heater wire circuit to one or more wires in the second heater wirecircuit, where the conductive tracks include electrical components suchas, for example and without limitation, diodes, transistors, capacitors,resistors, logic gates, integrated circuits, or the like. In certainembodiments, the intermediate connector includes a diode electricallycoupled to both the first heater wire circuit and the second heater wirecircuit. In certain embodiments, the inspiratory limb can furthercomprise a first sensor part or circuit having a first sensor positionedat the intermediate connector. In certain embodiments, the inspiratorylimb further comprises a second sensor circuit having a second sensorpositioned at a patient-end connector, the patient-end connector beingpositioned at a patient-end of the second segment of the inspiratorylimb. The inspiratory limb can be configured to operate in two sensingmodes. In a first sensing mode, signals from the first sensor arereceived without receiving signals from the second sensor. In a secondsensing mode, signals from the second sensor are received withoutreceiving signals from the first sensor. In some embodiments, sensingincludes receiving signals from both the first and second sensors inparallel. In such embodiments, an algorithm can determine a parametermeasured by the first sensor based at least in part on the signalsreceived in parallel from both the first and second sensors. In certainembodiments, the intermediate connector includes a diode electricallycoupled to both the first sensor circuit and the second sensor circuit.The patient-end connector can be configured to provide electricalconnections for the second sensor circuit. Similarly, the patient-endconnector can be configured to provide electrical connections for thesecond heater wire circuit. The sensors can be temperature sensors,humidity sensors, flow sensors, or the like. The first and secondsensors can be sensors configured to measure one or more parameters,such as temperature, humidity, flow rate, oxygen percentage, or thelike. In some embodiments, the first and second sensors are configuredto measure at least one like parameter (e.g., temperature, humidity,flow rate, etc.). In some embodiments, more than two sensors can beincluded and can be positioned at the intermediate connector and/or thepatient-end connector.

Some embodiments provide for a respiratory humidification system with aninspiratory limb and a controller. The inspiratory limb can include afirst segment having a first heater wire part or circuit, a secondsegment having a second heater wire part or circuit, an intermediateconnector having a connector circuit configured to electrically couplethe first heater wire circuit to the second heater wire circuit, a firstsensor positioned at a patient-end of the first segment, and a secondsensor positioned at a patient-end of the second segment. The controllercan be adapted to selectively switch between a first mode and a secondmode wherein in the first mode the controller provides electrical powerto the first heater wire circuit through the connector circuit and in asecond mode the controller provides electrical power to the first andsecond heater wire circuits. In certain embodiments, the respiratoryhumidification system switches between modes based at least in part oninput from one or both sensors. In certain embodiments, the switching isdone based at least in part on parameters including one or more oftemperature, flow, humidity, power, or any combination of these. Theparameters can be derived or obtained directly from the first sensor,the second sensor, or a combination of both sensors. In certainembodiments, the first and second modes are defined by a direction ofcurrent flow or a polarity of voltage provided by a power source. Insome embodiments, the respiratory humidification system can include morethan two sensors which provide input used to control heating of theinspiratory limb.

Some embodiments provide for a dual limb circuit that can include aninspiratory limb. Such an inspiratory limb can include a first segmenthaving a first heater wire part or circuit, a second segment of theinspiratory limb having a second heater wire part or circuit, anintermediate connector having a connector circuit configured toelectrically couple the first heater wire circuit to the second heaterwire circuit, a first sensor positioned at a patient-end of the firstsegment, and a second sensor positioned at a patient-end of the secondsegment. The dual limb circuit can also include an expiratory limb withan expiratory heater wire circuit. The dual limb system can furtherinclude an interface connected to the inspiratory limb and theexpiratory limb. The dual limb system can further include a controlleradapted to selectively switch between a first mode and a second modewherein in the first mode the controller provides electrical power tothe first heater wire circuit through the connector circuit and in asecond mode the controller provides electrical power to the first andsecond heater wire circuits. In certain embodiments, heating of theexpiratory limb is performed using the expiratory heater wire circuitindependent of the heating of the inspiratory limb using the first andsecond heater wire circuits. In certain embodiments, the expiratory limbis powered in parallel with the first heater wire circuit in the firstsegment of the inspiratory limb and/or in parallel with the first andsecond heater wire circuits. In certain embodiments, the expiratory limbcan be designed to be powered in only the first mode, only the secondmode, or in both the first mode and in the second mode. In certainembodiments, the interface is connected via a wye-piece. Any suitablepatient interface can be incorporated. Patient interface is a broad termand is to be given its ordinary and customary meaning to a person ofordinary skill in the art (that is, it is not to be limited to a specialor customized meaning) and includes, without limitation, masks (such astracheal mask, face masks and nasal masks), cannulas, and nasal pillows.

In some embodiments, a segmented inspiratory limb is provided, whereinthe structure of the segments comprise an elongate tube. The elongatetubes can include a first elongate member comprising a hollow bodyspirally wound to form at least in part a conduit having a longitudinalaxis, a lumen extending along the longitudinal axis, and a hollow wallsurrounding the lumen. The elongate tubes can include a second elongatemember spirally wound and joined between adjacent turns of the firstelongate member, the second elongate member forming at least a portionof the lumen of the elongate tube. In certain implementations, the firstelongate member forms in longitudinal cross-section a plurality ofbubbles with a flattened surface at the lumen. In certainimplementations, adjacent bubbles are separated by a gap above thesecond elongate member. In certain implementations, adjacent bubbles arenot directly connected to each other. In certain implementations, theplurality of bubbles has perforations.

In some embodiments, a medical conduit, such as an inspiratory limb, isprovided that comprises a conduit, a connector or cuff connected to oneend of the conduit for pneumatically coupling to a source of gases, aheater wire part, a sensor wire part, and an outlet for conveying gasestowards a desired destination. For example, the outlet may comprise aconnector or cuff for connecting to a patient interface. The heater wirepart may each comprise one or more heater wires running at least aportion of the length of the conduit so as to heat gases as they flowthrough the conduit. Similarly, one or more sensor wires may run atleast a portion of the length of the conduit, coupling a sensor to acontrol unit. While sensors may be positioned at any point, it is oftendesirable to include a temperature sensor at or proximate to apatient-end of the conduit so as to obtain an accurate indication of thetemperature of gases delivered to a patient. Consequently, someembodiments provide for both heater wire(s) and sensor wire(s) to runthe complete or substantially the complete length of the conduit.According to some embodiments, the patient-end of the heater wire partand the sensor wire part are connected to a common circuit board. One ormore sensors may be mounted to the board and read using the sensor wirepart.

In some embodiments, the heater wire part is connected to an AC supplyand the sensor wire part is also coupled thereto so as to enableselective reading of sensor(s) comprised in or coupled to the sensorwire part. According to some embodiments, a waveform of the AC supply ismonitored and/or known properties of the waveform are used to detect ordetermine the timing of one or more zero crossings (preferably fallingzero crossings) of the AC supply waveform. According to suchembodiments, the sensor(s) are preferably read at or about or after azero crossing. Preferably, the sensor is read within ±25 ms of a zerocrossing, more preferably ±15 ms, more preferably 10 ms, more preferably±5 ms, and more preferably still by about ±3 ms. According to somepresently preferred embodiments, the reading is taken with ±150 μs of azero crossing, more preferably ±100 μs of a zero crossing and morepreferably still ±50 μs of a zero crossing. The reduced ranges may beachieved by using interrupts to measure the sensor. These ranges areapplicable to other references to at or about or after a zero crossingbut for sake of brevity have not been repeated. Further, the sensor(s)are preferably read prior to the subsequent zero crossing of the sametype (i.e. rising or falling). Reading of the sensor(s) may be repeatedas desired, preferably with the zero crossing relationship maintained.Controlling reading of the sensor(s) in this manner can reduce sensorerrors close to zero since the interference of the power applied to theheater wire on the sensor wire signal is minimal. Further, changes tothe voltage polarity applied to at least some sensors (e.g. thermistors)can cause a disturbance in readings. Essentially, it takes a little timefor the signal to settle or stabilize and so preferably sensing occursover a time period immediately preceding a zero crossing.

In some embodiments, a medical conduit, such as an inspiratory limb, isprovided that comprises first and second segments. The two segments arepreferably arranged and joined or connectable such that gases flow froma first end of the first segment, to a second end of the first segment,to a first end of the second segment and then to a second end of thesecond segment. According to such embodiments, a first heater wire partmay be provided in the first segment and a second heater wire part maybe provided in the second segment. The first and second heater wireparts may be configurable in a first mode in which only the first heaterwire part is activated (i.e. generating heat) and in a second mode inwhich both the first and second heater wire parts are activated. Sucharrangements, as discussed previously, can be desirable where a conduitconveys gases through different environments, such as to an infantinside an incubator from outside thereof. A diode, for example, may beprovided intermediate the first and second heater wire parts such thatwhen current of an AC supply flows in one direction, only the firstheater wire part is powered and when the current flows in the otherdirection, both heater wire parts are powered. Other circuit/switchingarrangements may be used. According to some embodiments, at least onesensor may be provided at or proximate a second end of the secondsegment i.e. at a patient-end of the conduit. For example, a thermistormay be provided to measure a temperature of gases flowing in theconduit. Sensor wires may be provided to facilitate reading of thesensor(s). According to some embodiments, the sensor and heater wiresare connectable at or proximate to the first end of the first segment tothe AC supply and/or a controller. Such a connection may conveniently bemade via a cuff such as those described in PCT/NZ2013/000208. Where thesegments are releasably connectable, similar cuff connectors may be usedand reference is again made to PCT/NZ2013/000208. Similar to theprevious embodiment, the sensor may be mounted to a circuit board at orproximate to the second end of the second segment, with heater andsensor wires joined thereto. Preferably, a waveform of the AC supply ismonitored and/or known properties of the waveform are used to detect ordetermine the timing of one or more zero crossings (preferably fallingzero crossings) of the AC supply waveform. According to suchembodiments, the sensor(s) are preferably read at or about or after azero crossing. Further, the sensor(s) are preferably read prior to thesubsequent zero crossing of the same type. Reading of the sensor(s) maybe repeated as desired, preferably with the zero crossing relationshipmaintained. Controlling reading of the sensor(s) in this manner canreduce sensor errors close to zero.

As will be apparent to one skilled in the art, the preferred controlledreading of sensors timed with respect to falling zero crossings may beapplied to any embodiment described herein.

Embodiments further provide a controller for controlling reading of asensor associated with a medical conduit, the controller beingconfigured to read said sensor at or about or after a (preferablyfalling) zero crossing of an AC supply powering electrical circuitry ofthe medical conduit. Preferably, said reading is performed prior to thenext falling zero crossing of said AC supply of the same type. Furtherfeatures of the controller may be derived from the preceding statements.

Embodiments further provide a breathing assistance apparatus and/or arespiratory humidification system which is adapted to read a sensor ator about or after a (preferably falling) zero crossing of an associatedAC power supply. Preferably, said reading is performed prior to the nextzero crossing of said AC supply. Further features of the breathingassistance apparatus and/or respiratory humidification system may bederived from the preceding statements, and in fact said apparatus and/orsystem may include said conduits and/or said controller adapted tofacilitate said controlled reading of the sensor or sensors.

Embodiments also provide corresponding methods.

BRIEF DESCRIPTION OF THE DRAWINGS

Throughout the drawings, reference numbers can be reused to indicategeneral correspondence between reference elements. The drawings areprovided to illustrate example embodiments described herein and are notintended to limit the scope of the disclosure.

FIG. 1 is a schematic of a respiratory system to deliver respiratorygases to a patient.

FIG. 2 illustrates an example respiratory humidification system fordelivering humidified gas to a user, the respiratory humidificationsystem having a breathing circuit that includes a segmented inspiratorylimb with sensors in each segment.

FIG. 3 illustrates an example hardware configuration for a breathingcircuit with an inspiratory limb having a first and a second segment.

FIG. 4 illustrates an example hardware configuration for a breathingcircuit with an inspiratory limb.

FIG. 5 is a chart showing the relationship between the mains AC cycleand the heater wire cycles of the heater wires depicted in FIGS. 3 and 4.

FIG. 6 is a chart depicting measurement of sensors with respect to themains voltage waveform.

DETAILED DESCRIPTION

Certain embodiments and examples of medical circuit components includinginspiratory limbs, segmented inspiratory limbs and multiple-zone heatingare described herein. Those of skill in the art will appreciate that thedisclosure extends beyond the specifically disclosed embodiments and/oruses and obvious modifications and equivalents thereof. Thus, it isintended that the scope of the disclosure herein disclosed should not belimited by any particular embodiments described herein.

The disclosure references heater wires, heating elements, and/or heatersin the context of providing heat to a conduit. Heater wire, for example,is a broad term and is to be given its ordinary and customary meaning toa person of ordinary skill in the art (that is, it is not to be limitedto a special or customized meaning) and includes, without limitation,heater strips and/or conductive elements that produce heat whenelectrical power is provided. Examples of such heating elements includewires made of a conductive metal (e.g., copper), conductive polymers,conductive inks printed on a surface of a conduit, conductive materialsused to create a track on a conduit, and the like. Furthermore, thedisclosure references conduits, limbs, and medical tubes in the contextof gas delivery. Tube, for example, is a broad term and is to be givenits ordinary and customary meaning to a person of ordinary skill in theart and includes, without limitation, passageways having a variety ofcross-sections such as cylindrical and non-cylindrical passageways.Certain embodiments may incorporate a composite tube, which maygenerally be defined as a tube comprising two or more portions, or,specifically, in some embodiments, two or more components, as describedin greater detail below. The segmented limbs comprising the disclosedmedical tubes can also be used in breathing circuits such as acontinuous, variable, or bi-level positive airway pressure (PAP) systemor other form of respiratory therapy. The terms conduit and limb shouldbe construed in a manner that is similar to tube.

When a heated, humidified breathing tube is used for an incubator (orany region where there is a temperature change, such as around radiantwarmers used for burn victims, or under a blanket used by a patient),the breathing tube will pass through at least two distinct zones: alower temperature zone (such as the one outside the incubator) and ahigher temperature zone (such as the one inside the incubator). If thetube is heated along its full length, one of the zones will tend to beat an undesirable, unsuitable, or non-optimal temperature, depending onwhich zone is sensed (e.g., which zone contains a temperature sensor).If the heater wire is controlled to a sensor inside the incubator (suchas to a patient-end temperature sensor), the section outside theincubator will tend to be too cool, which can lead to condensation.Conversely, if the heater wire is controlled to a sensor outside theincubator, the section inside the incubator will tend to be too hot,which can lead to overheated gas being provided to the patient.Accordingly, some embodiments of the present disclosure describessystems and methods that provide for control over heat in a segmentedbreathing tube wherein each segment has an associated sensor providingfeedback to a control module. Although several embodiments are describedherein with respect to two zones, such a system could also be extendedto apply to uses with additional zones, segments, or regions. Forexample, in an embodiment comprising three temperature zones, segmentsof the breathing tube may be heated based at least in part on threedifferent temperature sensors in the zones. Furthermore, the embodimentsdisclosed herein can control the heat delivered to a breathing tubebased on a parameter at the patient-end, bypassing or ignoring one ormore of the sensors at intermediate points along the tube. Moreover, theembodiments disclosed herein can control the heat delivered to abreathing tube using parameters provided by sensors including, forexample and without limitation, temperature sensors, humidity sensors,flow sensors, oxygen sensors, and the like. Other embodiments, whileenabling different zones to be heated to different levels, may use fewersensors. For example, according to one embodiment, two segments areprovided and a single temperature sensor is associated with thebreathing tube, preferably at or towards or near a patient-end of thetube. According to this embodiment, the segments may be configured suchthat only a first segment is heated or both segments are heated, whereinthe first segment is preferably the segment most distal from the patientin terms of the gas flow path through the tube.

A control module can monitor and control the heating temperatures. Thecontrol module can be configured to provide heat to a first section ofthe breathing tube in a first mode and to the entire breathing tube in asecond mode using embodiments of connector assemblies described herein.The control module may detect the presence of the first and/or secondsection of the breathing tube. To achieve this, the presence and/orabsence of one or more sections of the breathing tube may be detected,with control of properties of the gases based at least in part modifiedaccordingly. The embodiments described herein can be used without flyingleads, exposed connectors, and/or patient-end electrical connections.Flying leads as used herein include electrical connections that extendexternally of the breathing tubes, internally through the breathingtubes, and incorporated, molded, or otherwise formed or included as partof the breathing tubes. The control module can be located within thehumidifier or externally to it. In some embodiments, the controller islocated within the humidifier to control the heater wires associatedwith a first segment of an inspiratory limb, a second segment of aninspiratory limb, and an expiratory limb as well as read parameters fromsensors associated with the first and second segments of the inspiratorylimb and/or the expiratory limb.

The control module can also adaptively change the temperature for thesegments. For example, the control module can monitor temperaturesensors associated with one or more segments. The monitoring can becontinuous, based on intervals, or other schemes such as interrupt orevent-based monitoring. For example, the monitoring of temperaturesensors can be based on reading values from an analog to digitalconverter, determining a voltage or current, sensing a logic condition,reading thermostatic devices, measuring thermistor values, measuringresistance temperature detectors, measuring the voltage of athermocouple, or other methods for sensing temperature, including, butnot limited to the use of semiconductor junction sensor, infrared orthermal radiation sensors, thermometers, indicators, or the like. Insome embodiments, the temperature sensors are thermistors.

In some embodiments, the ratio of the power delivered to the firstsegment of the inspiratory limb and the second segment of theinspiratory limb can change during use based at least in part onfeedback from sensor(s). For example, the ratio of power can be changedin a manner such that each segment is heated to a temperature to reduceor eliminate condensation. As a further example, the ratio of power canbe changed so that overheated gas is not provided to the patient. Insome embodiments, the ratio of power can be continuously changed basedon feedback from sensor(s) (e.g., temperature sensors, humidity sensors,oxygen sensors, flow sensors, etc.). The ratio of power can be changedin different ways. For example, the ratio of power can be changed byaltering the amplitude of a power signal (including, without limitation,the voltage and/or current), the duration of the power signal, the dutycycle of the power signal, or other suitable changes to the powersignal. In an embodiment, the ratio of power is changed by altering themagnitude of the current provided.

Some embodiments provide for an inspiratory limb comprising heater wiresthat are not within the gas path, but are contained within a materialthat separates them from the gas path and that also insulates them froman external environment. In some embodiments, the circuitry used toprovide power to heater wires and to read sensor(s) is internal to theinspiratory limb such that it is not exposed to the externalenvironment. In some segmented tube embodiments, the heater wire ismolded into the inspiratory or expiratory tube such that the ends of theheater wires in complementary segments of the tube contact anintermediate connector such that the heater wires electrically couple tothe intermediate connector, wherein the intermediate connector can beconfigured to provide circuitry for heater wire control and/or sensorreadings. In some embodiments, a duty cycle of a power source applied toa heater wire can be modified or varied to alter an amount of heatdelivered to a gas as it flows along the associated segment.

Some embodiments described herein provide for a respiratoryhumidification system that is configured to deliver warm, humidified gasto a patient or other user. The gas is passed through a liquid chamberwhich is filled with a liquid (e.g., water) that is heated using aheater plate. The liquid evaporates in the chamber and combines with thegas which flows over it, thereby heating and/or humidifying the gas. Thehumidified gas can be directed to an inspiratory limb having one or moreheater wires associated therewith. The heater wires can be selectivelypowered to provide a defined, desired, appropriate, or selected amountof heat to the humidified gas. In some embodiments, the respiratoryhumidification system can be used in conjunction with an incubator orradiant warmer. The inspiratory limb can be segmented such that a firstsegment is outside the incubator and a second segment is inside theincubator. Furthermore, a first set of heater wires can be associatedwith the first segment and a second set of heater wires can beassociated with the second segment. The humidification system can beconfigured to provide power to the first set of heater wires in a firstmode and to the first set and second set of heater wires in a secondmode. In some embodiments, the humidification system can be configuredto provide power to the first set of heater wires in a first mode and tothe second set of heater wires in a second mode. The inspiratory limbcan include sensors at the end of each segment or one segment to providefeedback to the humidification system for use in selecting a power todeliver to the sets of heater wires in the segments. In someembodiments, the humidification system can include an expiratory limbhaving associated heater wires which are also selectively controlled bythe humidification system. In this application, the segmented limb isdescribed with reference to an inspiratory limb. However, the describedfeatures can be applied to an expiratory limb, as well as other medicaltubes.

Respiratory Humidification Systems

FIG. 1 shows a respiratory system 1 which can include, but is notlimited to, the following components: a pressurized gases source 2, suchas a blower or ventilator, adapted to generate a supply of gases to bedelivered to a patient 3; a humidification device 4 adapted to conditionthe supply of gases; a medical tube 6 adapted to deliver the gases to apatient interface 8, which then delivers the gases to the patient 3; anda connector 16 adapted to connect the medical tube 6 to thehumidification device 4.

The patient interface 8 as described herein may refer to a mask, nasalmask, nasal prongs, oral mask, tracheal mask, or nasal pillows.

The humidification device 4 as described herein may refer to any devicethat conditions gases. This may include heating the gases and/orhumidifying the gases.

Gases as described herein may refer to air, oxygen, carbon dioxide, or amixture of any such gases, or a combination of any such gases with oneor more medicaments or aerosols that may be delivered to the patient 3via the patient interface 8.

The medical tube 6 as described herein may refer to a tube, conduit,circuit, or hose. The medical tube 6 may comprise one or more wires. Theone or more wires may comprise at least one heater wire, at least onesensor wire, and/or any other type of electrical conductor. The one ormore wires may be within the medical tube 6. The one or more wires maybe lying along an inner or outer surface of the medical tube 6. The oneor more wires may be spirally wound onto the medical tube 6 or into themedical tube 6 such that the one or more wires may be embedded in thewall of the medical tube 6.

The medical tube 6 is preferably heated. The medical tube 6 may includeinsulation to reduce condensate from forming within the medical tube 6.Condensate may form if heated, humidified gases within the medical tube6 cool down during transit. To reduce or eliminate condensate formation,the medical tube 6 may be heated. This heating may be provided by theone or more wires comprising one or more heater wires.

A terminating portion of the medical tube 6 may be provided to terminatethe one or more wires at a connector 16 such that an electricalconnection may be formed between the medical tube 6 and a component ofthe respiratory system 1. The connector 16 may provide a pneumaticconnection between the medical tube 6 and a component of the respiratorysystem 1. A component of the respiratory system 1 as described hereinmay refer to a patient interface or a humidification device. Theconnector 16 may provide either one of or both an electrical andpneumatic connection between the medical tube 6 and a component of therespiratory system 1.

The one or more wires may also comprise one or more sensing wires. Theone or more sensing wires may be used to sense gases properties such astemperature, flow, humidity, or pressure. In some embodiments, the oneor more sensing wires may be used to sense temperature. In someembodiments, the one or more sensing wires may be connected to one ormore sensors that may be used to sense one or more of these gasesproperties.

FIG. 2 illustrates another example respiratory humidification system 100for delivering humidified gas to a user, the respiratory humidificationsystem 100 having a breathing circuit 200 that includes a segmentedinspiratory limb 202 with sensors 204 a, 204 b in each segment. Thesegmented inspiratory limb 202 can be used in conjunction with anincubator 208, as illustrated, or with another system where there aredifferent temperatures along different segments of the inspiratory limb202, such as in conjunction with a radiant warmer. The segmentedinspiratory limb 202 can be used to provide different levels of heat todifferent segments of the inspiratory limb 202 a, 202 b to reduce orprevent condensation and/or to control a temperature of gas delivered toa user.

The respiratory humidification system 100 comprises a pressurized gassource 102. In some implementations, the pressurized gas source 102comprises a fan, blower, or the like. In some implementations, thepressurized gas source 102 comprises a ventilator or other positivepressure generating device. The pressurized gas source 102 comprises aninlet 104 and an outlet 106.

The pressurized gas source 102 provides a flow of fluid (e.g., oxygen,anesthetic gases, air or the like) to a humidification unit 108. Thefluid flow passes from the outlet 106 of the pressurized gas source 102to an inlet 110 of the humidification unit 108. In the illustratedconfiguration, the humidification unit 108 is shown separate of thepressurized gas source 102 with the inlet 110 of the humidification unit108 connected to the outlet 106 of the pressurized gas source 102 with aconduit 112. In some implementations, the pressurized gas source 102 andthe humidification unit 108 can be integrated into a single housing.

While other types of humidification units can be used with certainfeatures, aspects, and advantages described in the present disclosure,the illustrated humidification unit 108 is a pass-over humidifier thatcomprises a humidification chamber 114 and an inlet 110 to thehumidification chamber 114. In some implementations, the humidificationchamber 114 comprises a body 116 having a base 118 attached thereto. Acompartment can be defined within the humidification chamber 116 that isadapted to hold a volume of liquid that can be heated by heat conductedor provided through the base 118. In some implementations, the base 118is adapted to contact a heater plate 120. The heater plate 120 can becontrolled through a controller 122 or other suitable component suchthat the heat transferred into the liquid can be varied and controlled.

The controller 122 of the humidification unit 108 can control operationof various components of the respiratory humidification system 100.While the illustrated system is illustrated as using a single controller122, multiple controllers can be used in other configurations. Themultiple controllers can communicate or can provide separate functionsand, therefore, the controllers need not communicate. In someimplementations, the controller 122 may comprise a microprocessor, aprocessor, or logic circuitry with associated memory or storage thatcontains software code for a computer program. In such implementations,the controller 122 can control operation of the respiratoryhumidification system 100 in accordance with instructions, such ascontained within the computer program, and also in response to internalor external inputs. The controller 122, or at least one of the multiplecontrollers, can be located with the breathing circuit, either attachedto the breathing circuit or integrated as part of the breathing circuit.

The body 116 of the humidification chamber 114 comprises a port 124 thatdefines the inlet 110, and a port 126 that defines an outlet 128 of thehumidification chamber 114. As liquid contained within thehumidification chamber 114 is heated, liquid vapor is mixed with gasesintroduced into the humidification chamber 114 through the inlet port124. The mixture of gases and vapor exits the humidification chamber 114through the outlet port 126.

The respiratory humidification system 100 includes a breathing circuit200 comprising the inspiratory limb 202 connected to the outlet 128 thatdefines the outlet port 126 of the humidification unit 108. Theinspiratory limb 202 conveys toward a user the mixture of gases andwater vapor that exits the humidification chamber 114. The inspiratorylimb 202 can include a heating element 206 positioned along theinspiratory limb 202, wherein the heating element 206 is configured toreduce condensation along the inspiratory limb 202, to control atemperature of gas arriving at the user, to maintain humidity of thegas, or any combination of these. The heating element 206 can raise ormaintain the temperature of the gases and water vapor mixture beingconveyed by the inspiratory limb 202. In some implementations, theheating element 206 can be a wire that defines a resistance heater. Byincreasing or maintaining the temperature of the gases and water vapormixture leaving the humidification chamber 114, the water vapor is lesslikely to condensate out of the mixture.

The respiratory humidification system 100 can be used in conjunctionwith an incubator 208. The incubator 208 can be configured to maintain adesired environment for a user within the incubator 208, such as aselected, defined, or desired temperature. Within the incubator 208,therefore, an interior ambient temperature may be different than atemperature outside the incubator 208. Thus, the incubator 208 causes,defines, creates, or maintains different temperature zones along theinspiratory limb 202, where the interior temperature is typically hotterthan the exterior temperature. Having at least two different temperaturezones along the inspiratory limb 202 can create problems during deliveryof gas to a user such as condensation along the inspiratory limb 202,delivering a gas that has a temperature that is too high, or both.

The respiratory humidification system 100 can include an expiratory limb210 with associated heating element 212. In some embodiments, theexpiratory limb 210 and the inspiratory limb 202 can be connected usinga suitable fitting (e.g., a wye-piece). In some embodiments, therespiratory humidification system 100 can be used in conjunction with aradiant warmer, under a blanket, or in other systems or situations thatcreate two or more temperature zones. The systems and methods describedherein can be used with such systems and are not limited toimplementations incorporating incubators.

The inspiratory limb 202 can be divided into segments 202 a and 202 bwhere a first segment 202 a can be a portion of the inspiratory limb 202that is outside the incubator 208 and a second segment 202 b (e.g., anincubator extension), can be a portion of the inspiratory limb 202 thatis inside the incubator 208. The first and second segments 202 a, 202 bcan be different lengths or the same length. In some embodiments, thesecond segment 202 b can be shorter than the first segment 202 a, and,in certain implementations, the second segment 202 b can be about halfas long as the first segment 202 a. The first segment 202 a, forexample, can have a length that is at least about 0.5 m and/or less thanor equal to about 2 m, at least about 0.7 m and/or less than or equal toabout 1.8 m, at least about 0.9 m and/or less than or equal to about 1.5m, or at least about 1 m and/or less than or equal to about 1.2 m. Thesecond segment 202 b, for example, can have a length that is at leastabout 0.2 m and/or less than or equal to about 1.5 m, at least about 0.3m and/or less than or equal to about 1 m, at least about 0.4 m and/orless than or equal to about 0.8 m, or at least about 0.5 m and/or lessthan or equal to about 0.7 m.

The segments of the inspiratory limb 202 a, 202 b can be coupled to oneanother to form a single conduit for gas delivery. In some embodiments,the first segment 202 a can include one or more first heater wires 206 aand one or more first sensors 204 a and can be used without the secondsegment 202 b. The controller 122 can be configured to control the firstheater wires 206 a and read the first sensor 204 a without the secondsegment 202 b being coupled to the first segment 202 a. Furthermore,when the second segment 202 b is coupled to the first segment 202 a, thecontroller 122 can be configured to control the first and second heaterwires 206 a, 206 b and read the first and second sensors 204 a, 204 b intheir respective segments. In some embodiments, the controller 122 canbe configured to control the respective first and second heater wires206 a, 206 b and to read the respective first and second sensors 204 a,204 b when the second segment 202 b is attached; and to control thefirst heater wires 206 a and to read the first sensor 204 a when thesecond segment 202 b is not attached, without modification to thecontroller 122 or humidification unit 108. Thus, the same controller 122and/or humidification unit 108 can be used whether the inspiratory limb202 includes both the first and second segments 202 a, 202 b or only thefirst segment 202 a. In some embodiments, the controller 122 can befurther configured to control the heater wires 212 in the expiratorylimb 210 without modification to the controller 122 or humidificationunit 108. Accordingly, the respiratory humidification system 100 canfunction with or without the second segment 202 b attached and/or withor without the expiratory limb 210 attached.

In some embodiments, the first and second segments 202 a, 202 b arepermanently joined together to form a single conduit for gas delivery.As used here, permanently joined can mean that the segments 202 a, 202 bare joined together in a manner that makes it difficult to separate thesegments, such as through the use of adhesives, friction fits,over-molding, mechanical connectors, and the like. In some embodiments,the first and second segments 202 a, 202 b are configured to bereleasably coupled. For example, the first segment 202 a can be used forgas delivery without the second segment 202 b, or the first and secondsegments 202 a, 202 b can be coupled together to form a single conduitfor gas delivery. In some embodiments, the first and second segments 202a, 202 b can be configured such that they can be coupled together inonly one configuration. For example, the first segment 202 a can have adefined chamber-end (e.g., an end closest to the chamber 114 orhumidification unit 108 along a direction of the flow of the humidifiedgas to the patient) and a defined patient-end (e.g., an end closest tothe patient along a direction of the flow of the humidified gas to thepatient) wherein the chamber-end is configured to couple to componentsat the chamber 114 and/or humidification unit 108. The second segment202 b can have a defined chamber-end and a defined-patient end whereinthe chamber-end is configured to only couple to the patient-end of thefirst segment 202 a. The chamber-end of the first segment 202 a can beconfigured to not couple with either end of the second segment 202 b.Similarly, the patient-end of the first segment 202 a can be configuredto not couple with the patient-end of the second segment 202 b.Similarly, the patient-end of the second segment 202 b can be configuredto not couple with either end of the first segment 202 a. Accordingly,the first and second segments 202 a, 202 b can be configured to becoupled in only one way to form a single conduit for gas delivery. Insome embodiments, the first and second segments 202 a, 202 b can beconfigured to be coupled in a variety of configurations. For example,the first and second segments 202 a, 202 b can be configured to notinclude a defined patient-end and/or a defined chamber-end. As anotherexample, the first and second segments 202 a, 202 b can be configuredsuch that the patient-end and/or the chamber-end of the first segment202 a can couple to either the chamber-end or the patient-end of thesecond segment 202 b. Similarly, the first and second segments 202 a,202 b can be configured such that the chamber-end and/or the patient-endof the second segment 202 a can couple to either the chamber-end or thepatient-end of the second segment 202 b.

The respiratory humidification system 100 can include an intermediateconnector 214 that can be configured to electrically couple elements ofthe first and second segments 202 a, 202 b of the inspiratory limb 202.The intermediate connector 214 can be configured to electrically couplethe heater wires 206 a in the first segment 202 a to the heater wires206 b in the second segment 202 b to enable control of the heater wires206 a, 206 b using the controller 122. The intermediate connector 214can be configured to electrically couple the second sensor 204 b in thesecond segment 202 b to the first sensor 204 a in the first segment toenable the controller 122 to acquire their respective outputs. Theintermediate connector 214 can include electrical components that enableselective control of the heater wires 206 a, 206 b and/or selectivereading of the sensors 204 a, 204 b. For example, the intermediateconnector 214 can include electrical components that direct powerthrough the first heater wires 206 a in a first mode and through thefirst and second heater wires 206 a, 206 b in a second mode. Theelectrical components included on the intermediate connector 214 caninclude, for example and without limitation, resistors, diodes,transistors, relays, rectifiers, switches, capacitors, inductors,integrated circuits, micro-controllers, micro-processors, RFID chips,wireless communication sensors, and the like. In some embodiments, theintermediate connector 214 can be configured to be internal to theinspiratory limb 202 such that it is substantially shielded fromexternal elements (e.g., less than 1% of the water, particulates,contaminates, etc. from an environment external to the inspiratory limb202 contacts the intermediate connector 214). In some embodiments, someof the electrical components on the intermediate connector 214 can beconfigured to be physically isolated from the humidified gas within theinspiratory limb 202 to reduce or prevent damage that may result fromexposure to humidity. In some embodiments, the intermediate connector214 can include relatively inexpensive passive electrical components toreduce cost and/or increase reliability.

The inspiratory limb 202 can include sensors 204 a, 204 b in respectivesegments of the inspiratory limb 202 a, 202 b. The first sensor 204 acan be positioned near an end of the first segment 202 a, close to theincubator 208 so that the parameter derived from the first sensor 204 acorresponds to a parameter of the humidified gas entering the secondsegment 202 b. The second sensor 204 b can be positioned near an end ofthe second segment 202 b so that the parameter derived from the secondsensor 204 b corresponds to a parameter of the humidified gas deliveredto the patient or user. The output of the sensors 204 a, 204 b can besent to the controller 122 as feedback for use in controlling powerdelivered to the heating elements 206 a, 206 b of the segments of theinspiratory limb 202 a, 202 b. In some embodiments, one or both of thesensors 204 a, 204 b can be temperature sensors, humidity sensors,oxygen sensors, flow sensors, or the like. A temperature sensor can beany suitable type of temperature sensor including, for example andwithout limitation, a thermistor, thermocouple, digital temperaturesensor, transistor, and the like. The parameters provided by or derivedfrom the sensors can include, for example and without limitation,temperature, humidity, oxygen content, flow rate, or any combination ofthese or the like.

The controller 122 can be configured to control the heater wires 206 aand 206 b, to receive feedback from the sensors 204 a and 204 b, toprovide logic to control power to the heater wires 206 a and 206 b, toadjust control of the heater wires 206 a and 206 b in response toreadings from the sensors 204 a and 204 b, to detect a presence of asecond segment 202 b of the inspiratory limb 202 (for example, thesecond segment 202 b may have an identification element associatedtherewith such as a dedicated resistor or other element specifically orpredominantly used for identification purposes or an inherentcharacteristic of the second segment may be used, such as a thermistorhave a resistance within a predetermined range), to derive parametersfrom the readings from the sensors 204 a and 204 b, and the like. Insome embodiments, the controller 122 includes a power source configuredto deliver electrical power to the heater wires. The power source can bea source of alternating current or direct current. In some embodiments,the controller 122 can receive input from a heater plate sensor 130. Theheater plate sensor 130 can provide the controller 122 with informationregarding a temperature and/or power usage of the heater plate 120. Insome embodiments, the controller 122 can receive input from a flowsensor 132. Any suitable flow sensor 132 can be used and the flow sensor132 can be positioned between ambient air and the humidification chamber114 or between the pressurized gas source 102 and the humidificationchamber 114. In the illustrated system, the flow sensor 132 ispositioned on the inlet port 124 of the humidification chamber 114.

Detection of the presence of the second segment may be used to alter thecontrol of the apparatus. For example, control algorithms adapted forproviding humidified gases to an infant inside an incubator may be used.Thus, applicable temperature profiles and/or values and/or ranges may beused and flow and/or pressures of the gases delivered may be adjusted.

Breathing Circuit Hardware Configurations

FIG. 3 illustrates an example diagram of a hardware configuration 800for a breathing circuit 200 having a first segment 202 a of aninspiratory limb, a second segment 202 b of the inspiratory limb, andmay include an expiratory limb (not shown) or exhaled gases may bevented to the atmosphere. The hardware configuration 800 can include ahumidifier 108 configured to couple the wiring of the heater wires HW1,and the wiring for sensor 204. In some embodiments, the sensor cartridge802 can be configured to couple the wiring of the heater wires HW1 andthe wiring for sensor 204. The heater wires HW1 can be controlled in twomodes. In a first mode, the first heater wires 206 a receive electricalpower while the second heater wires 206 b do not. In a second mode, thefirst and second heater wires 206 a, 206 b receive electrical power.

The hardware configuration 800 can include an intermediate printedcircuit board (PCB) 214 that includes a power diode D1 The intermediatePCB 214 can include heat pads to dissipate heat generated by the diodeD1 to reduce the effects on the sensor 204. The hardware configuration800 can include a patient-end PCB 804 having two heater wires and asensor 204, wherein the heater wires 206 b are directly electricallycoupled. In the first mode of operation, electrical power can beprovided to HW1 such that current flows through heater wires 206 a andthrough diode D1 while substantially no current flows through heaterwires 206 b (e.g., less than 1% of the current through heater wires 206a flows through heater wires 206 b). In the second mode of operation,electrical power can be provided to HW1 such that current flows throughheater wires 206 a and 206 b. The first and second modes of operationcan be controlled at least in part by the direction of the current flowthrough the heater wires HW1.

In some embodiments, the sensor cartridge 802 can be located within thehumidification system 100 or external to the system.

FIG. 4 illustrates an example diagram of a hardware configuration 900for an inspiratory limb 6 of a respiratory system 1 that may include anexpiratory limb (not shown) or exhaled gases may be vented to theatmosphere. The hardware configuration 900 can include a humidifier 4configured to couple the wiring of the heater wires HW1, and the wiringfor sensor 204. In some embodiments, the sensor cartridge 802 can beconfigured to couple the wiring of the heater wires HW1 and the wiringfor sensor 204.

The hardware configuration 900 can include a patient-end PCB 804 havingtwo heater wires and a sensor 204, wherein the heater wires 206 aredirectly electrically coupled. Electrical power can be provided to HW1such that current flows through heater wires 206 and generate heat.

Other configurations, including embodiments in which an expiratory limbis heated and/or where one or more additional sensors are provided, canbe derived without invention from PCT/NZ2013/00208 but implementing thenovel sensor reading control disclosed herein.

Embodiments of the systems shown in FIGS. 1-4 may include a sinusoidalpulse width modulation (SPWM) driver that provides for turning a heaterplate and heater wires ON or OFF, the heater plate for heating thecontents of a humidification chamber and the heater wires being, forexample, the heater wires HW1 of an inspiratory conduit. The driver maysupply, for example, two 100-bit patterns, one for the heater plate andone for the heater wire. Each bit in a bit pattern may cause the SPWMdriver to switch the respective heater ON or OFF. Switching may be doneat each falling zero crossing of the mains voltage to reduce the stresson the power supply that would be caused by an abrupt transition fromzero power to the maximum power level. The choice of falling edge orrising edge is somewhat arbitrary, what is important is that the switchoccurs at the zero crossing and only every full AC cycle. Thus, theheaters can be switched ON or OFF 50 times per second (every 20 ms) or60 times per second (every 16.67 ms) for 50 Hz mains and 60 Hz mains,respectively. This is useful because the sensor, e.g. a patient-endthermistor, measurement cycle can be aligned with the mains cycle, themains and heater wire cycles already being aligned.

FIG. 5 is a chart showing the relationship between the mains AC cycleand the heater wire cycles of the heater wires depicted in FIGS. 3 and 4.

FIG. 6 is a chart depicting measurement of sensors with respect to themains voltage waveform. When the falling zero crossing occurs on themains cycle, various setup steps may be taken to prepare for the sensorreading, including switching the polarity on the sensing wire topositive. As the rising zero occurs on the mains cycle, the measurementis taken and the polarity on the sensing wire is reversed. The fallingzero crossing and frequency may be detected by analyzing the mainsvoltage with the rising zero crossing being predicted.

CONCLUSION

Examples of respiratory humidification systems with sensor readingcontrol and associated components and methods have been described withreference to the figures. The figures show various systems and modulesand connections between them. The various modules and systems can becombined in various configurations and connections between the variousmodules and systems can represent physical or logical links. Therepresentations in the figures have been presented to clearly illustrateprinciples related to providing sensor reading control, and detailsregarding divisions of modules or systems have been provided for ease ofdescription rather than attempting to delineate separate physicalembodiments. The examples and figures are intended to illustrate and notto limit the scope of the inventions described herein. For example, theprinciples herein may be applied to a respiratory humidifier as well asother types of humidification systems, including surgical humidifiers.The principles herein may be applied in respiratory applications as wellas in other scenarios where a temperature of gases is to be controlledalong multiple segments subject to varying ambient temperatures.

As used herein, the term “processor” refers broadly to any suitabledevice, logical block, module, circuit, or combination of elements forexecuting instructions. For example, controllers, as referred to herein,can include any conventional general purpose single- or multi-chipmicroprocessor such as a Pentium® processor, a MIPS® processor, a PowerPC® processor, AMD® processor, ARM® processor, or an ALPHA® processor.In addition, controllers can include any conventional special purposemicroprocessor such as a digital signal processor or a microcontroller.The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein can be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA), or other programmable logicdevice, discrete gate or transistor logic, discrete hardware components,or any combination thereof designed to perform the functions describedherein, or can be a pure software in the main processor. For example,logic module 504 can be a software-implemented function block which doesnot utilize any additional and/or specialized hardware elements.Controllers can be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a combination of amicrocontroller and a microprocessor, a plurality of microprocessors,one or more microprocessors in conjunction with a DSP core, or any othersuch configuration.

Data storage can refer to electronic circuitry that allows data to bestored and retrieved by a processor. Data storage can refer to externaldevices or systems, for example, disk drives or solid state drives. Datastorage can also refer to fast semiconductor storage (chips), forexample, Random Access Memory (RAM) or various forms of Read Only Memory(ROM), which are directly connected to a communication bus orcontroller. Other types of data storage include bubble memory and corememory. Data storage can be physical hardware configured to store datain a non-transitory medium.

Although certain embodiments and examples are disclosed herein,inventive subject matter extends beyond the specifically disclosedembodiments to other alternative embodiments and/or uses, and tomodifications and equivalents thereof. Thus, the scope of the claims orembodiments appended hereto is not limited by any of the particularembodiments described herein. For example, in any method or processdisclosed herein, the acts or operations of the method or process can beperformed in any suitable sequence and are not necessarily limited toany particular disclosed sequence. Various operations can be describedas multiple discrete operations in turn, in a manner that can be helpfulin understanding certain embodiments; however, the order of descriptionshould not be construed to imply that these operations are orderdependent. Additionally, the structures described herein can be embodiedas integrated components or as separate components. For purposes ofcomparing various embodiments, certain aspects and advantages of theseembodiments are described. Not necessarily all such aspects oradvantages are achieved by any particular embodiment. Thus, for example,various embodiments can be carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other aspects or advantages as can also be taughtor suggested herein.

Conditional language used herein, such as, among others, “can,” “could,”“might,” “may,” “e.g.,” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orstates. Thus, such conditional language is not generally intended toimply that features, elements and/or states are in any way required forone or more embodiments. As used herein, the terms “comprises,”“comprising,” “includes,” “including,” “has,” “having” or any othervariation thereof, are intended to cover a non-exclusive inclusion. Forexample, a process, method, article, or apparatus that comprises a listof elements is not necessarily limited to only those elements but mayinclude other elements not expressly listed or inherent to such process,method, article, or apparatus. Also, the term “or” is used in itsinclusive sense (and not in its exclusive sense) so that when used, forexample, to connect a list of elements, the term “or” means one, some,or all of the elements in the list. Conjunctive language such as thephrase “at least one of X, Y and Z,” unless specifically statedotherwise, is otherwise understood with the context as used in generalto convey that an item, term, etc. may be either X, Y or Z. Thus, suchconjunctive language is not generally intended to imply that certainembodiments require at least one of X, at least one of Y and at leastone of Z each to be present. As used herein, the words “about” or“approximately” can mean a value is within +10%, within +5%, or within±1% of the stated value.

Methods and processes described herein may be embodied in, and partiallyor fully automated via, software code modules executed by one or moregeneral and/or special purpose computers. The word “module” refers tologic embodied in hardware and/or firmware, or to a collection ofsoftware instructions, possibly having entry and exit points, written ina programming language, such as, for example, C or C++. A softwaremodule may be compiled and linked into an executable program, installedin a dynamically linked library, or may be written in an interpretedprogramming language such as, for example, BASIC, Perl, or Python. Itwill be appreciated that software modules may be callable from othermodules or from themselves, and/or may be invoked in response todetected events or interrupts. Software instructions may be embedded infirmware, such as an erasable programmable read-only memory (EPROM). Itwill be further appreciated that hardware modules may comprise connectedlogic units, such as gates and flip-flops, and/or may comprisedprogrammable units, such as programmable gate arrays, applicationspecific integrated circuits, and/or processors. The modules describedherein can be implemented as software modules, but also may berepresented in hardware and/or firmware. Moreover, although in someembodiments a module may be separately compiled, in other embodiments amodule may represent a subset of instructions of a separately compiledprogram, and may not have an interface available to other logicalprogram units.

In certain embodiments, code modules may be implemented and/or stored inany type of computer-readable medium or other computer storage device.In some systems, data (and/or metadata) input to the system, datagenerated by the system, and/or data used by the system can be stored inany type of computer data repository, such as a relational databaseand/or flat file system. Any of the systems, methods, and processesdescribed herein may include an interface configured to permitinteraction with users, operators, other systems, components, programs,and so forth.

It should be emphasized that many variations and modifications may bemade to the embodiments described herein, the elements of which are tobe understood as being among other acceptable examples. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and protected by the following claims.Further, nothing in the foregoing disclosure is intended to imply thatany particular component, characteristic or process step is necessary oressential.

1.-39. (canceled)
 40. A controller for a breathing assistance apparatus,the breathing assistance apparatus comprising a conduit for conveyinggases therein, the conduit comprising first and second segments that areintegral or connectable to provide an extended conduit, the conduitfurther comprising circuitry, wherein the circuitry comprises at leastone heater wire part configured to heat the gases in the conduit, inuse, and at least one sensor wire part comprising at least one sensorconfigured to monitor a parameter of the gases in the conduit, in use,the controller being configured to: receive a signal indicative of apresence or absence of one or both the first segment or the secondsegment so as to implement control dependent on which segment(s) is/aredetermined to be present or absent; control application of an AC powerwaveform to the at least one heater wire part; and control selectivereading of the at least one sensor, wherein the controller is configuredto read the at least one sensor at or about a particular portion of theAC power waveform provided to the at least one heater wire part.
 41. Thecontroller of claim 40, wherein said particular portion of the AC powerwaveform commences at or about or after a first zero crossing of the ACpower waveform, and terminates at or before a second, subsequent zerocrossing of the AC power waveform, the first zero crossing and thesecond, subsequent zero crossing being consecutive zero crossings of asame type, wherein types of zero crossings include a rising zerocrossing and a falling zero crossing.
 42. The controller of claim 41,wherein the first zero crossing is a falling zero crossing.
 43. Thecontroller of claim 40, wherein the at least one sensor comprises two ormore sensors, at least one of the two or more sensors located in thefirst segment and at least another one of the two or more sensorslocated in the second segment, the controller being configured toreceive sensed readings from each of said two or more sensors.
 44. Thecontroller of claim 43, wherein the controller is further configured to:control reading of a first of said two or more sensors commencing at orabout or after a first particular portion of the AC power waveform, andcontrol reading of a second of said two or more sensors commencing at asecond particular portion of the AC power waveform, wherein the firstand second particular portions are consecutive particular portions. 45.The controller of claim 40, wherein: in response to determining thatonly the first segment is present, the controller adopts a first mode,the first mode adapted for adult users and/or applications in whichsurrounding environmental conditions are substantially the same along alength of the conduit; or in response to determining that the first andsecond segments are both present, the controller adopts a second mode,the second mode adapted for incubators and/or applications in which thesurrounding environmental conditions are variable along the length ofthe conduit.
 46. The controller of claim 45, wherein the controller isfurther configured to switch between the first mode and the second modedependent, at least in part, on the selective reading of the at leastone sensor.
 47. The controller of claim 40, wherein the controller isfurther configured to control the application of the AC power waveformto the at least one heater wire part such that: the AC power waveformapplied to the at least one heater wire part transitions from flat to anegative half of a full cycle, and/or the AC power waveform applied tothe at least one heater wire part transitions from a positive half ofthe full cycle to flat.
 48. The controller of claim 40, wherein said atleast one heater wire part comprises first and second heater wire parts,the first segment comprising the first heater wire part and the secondsegment comprising the second heater wire part, wherein, in response todetermining that the first segment and the second segment are bothpresent, the controller is configured to: control selective applicationof the AC power waveform during a first time period to the first heaterwire part only, and control selective application of the AC powerwaveform in a second time period to both the first and second heaterwire parts or to the second heater wire part only.
 49. The controller ofclaim 48, wherein the controller is further adapted to control theapplication of the AC power waveform: to the first said heater wire partsuch that the AC power waveform transitions: from flat to a first of twopositive half cycles; and/or to flat following the two positive halfcycles, or to the second said heater wire part such that the AC powerwaveform transitions: from flat or off to a first of two negative halfcycles; and/or to flat following the two negative half cycles, or toboth the first and second said heater wire parts such that the AC powerwaveform transitions: from flat or off to the first of the two negativehalf cycles; and/or to flat following the two negative half cycles. 50.The controller of claim 40, wherein the breathing assistance apparatuscomprises an inspiratory limb, the inspiratory limb comprising the firstand second segments and the at least one heater wire part including afirst heater wire part and a second heater wire part, the breathingassistance apparatus further comprising an expiratory limb, theexpiratory limb comprising a third segment, wherein the third segmentcomprises at least one third heater wire part to heat the gases in theexpiratory limb, the controller being configured to control theapplication of the AC power waveform to the at least one third heaterwire part: independent of heating of the first and second heater wireparts; in parallel with the first heater wire part; and/or in parallelwith the first and second heater wire parts.
 51. The controller of claim40, wherein at least a portion of said at least one sensor wire part ispositioned adjacent at least a corresponding portion of said at leastone heater wire part.
 52. The controller of claim 40, wherein the secondsegment comprises an identification element, wherein the signal receivedby the controller is dependent on the identification element.
 53. Thecontroller of claim 52, wherein the identification element comprises anelement or an inherent characteristic of the second segment.
 54. Thecontroller of claim 40, wherein the controller is further configured tocontrol a direction of a current flow of the AC power waveform throughthe at least one heater wire part and/or a voltage polarity of the ACpower waveform through the at least one heater wire part.
 55. Thecontroller of claim 54, wherein the at least one heater wire part isconfigured such that when a current flows in a first direction, only thefirst segment is powered and when the current flows in a seconddirection, both the first and second segments are powered.
 56. Thecontroller of claim 55, wherein the controller is further configured toadjust the application of the AC power waveform to the at least oneheater wire part based on the selective reading of the at least onesensor.
 57. The controller of claim 40, wherein the conduit comprisesadditional segments in addition to the first segment and the secondsegment.
 58. The controller of claim 40, further comprising amultiplexor, and the at least one sensor comprising two or more sensors,the multiplexor coupled to the at least one sensor wire part to enablereading of a corresponding sensor of the two or more sensors.
 59. Abreathing assistance apparatus comprising: a pressurized gas source toprovide a flow of fluid; a humidification unit to humidify the fluid, inuse, the humidification unit comprising the controller as claimed inclaim 43; and an outlet connectable to the conduit for conveying gasestherein, the conduit comprising: the first and second segments that areintegral, or connectable together, to provide the extended conduit, thefirst and second segments each having the at least one or another one ofthe two or more sensors for monitoring the parameter of the gases in theconduit, in use, and the circuitry comprising the at least one heaterwire part to heat gases in the conduit.